CN105357752A - Time synchronization method and apparatus for wireless ad-hoc network - Google Patents

Abstract

The embodiments of the invention provide a time synchronization method and apparatus for a wireless ad-hoc network, and are applied to a first node in a wireless ad-hoc network. The method provided by one concrete embodiment of the invention comprises the following steps: in an interception period of a current synchronization period, monitoring whether first synchronization signals from other nodes are received, wherein any one node in the wireless ad-hoc network in each synchronization period successively goes through a waiting period, a signal sending period, a no-response period and an interception period; if so, adjusting a current phase of the first node according to the first synchronization signals, if the phase reaches a threshold after adjustment, setting the phase to zero, entering the waiting period of the next synchronization period in advance, and preparing to send synchronization signals; and otherwise, controlling linear increase of the phase, and when the phase is increased to the threshold, entering the waiting period of the next synchronization period. According to the embodiments of the invention, high-precision time synchronization in the wireless ad-hoc network can be realized.

Description

For method for synchronizing time and the device of wireless self-networking

Technical field

The present invention relates to wireless communication technology field, particularly relate to a kind of method for synchronizing time for wireless self-networking and device.

Background technology

Compared with traditional cellular network, wireless self-networking does not have master controller, and all Node distribution formulas are run, and do not need to rely on existing fixed communication network infrastructure, and can launch rapidly to use, required manual intervention is few, and in network, all nodes are equal.Each network node cooperates mutually, undertaken communicating by wireless link, exchange message, realize sharing of information and service, network node can enter dynamically, optionally, continually and leave network, and usually do not need to warn in advance or notify, and the communication of other nodes in network can not be destroyed.Therefore, there is good quickly networking and withstand wreckD energy, be adapted at working in the incompetent environment of conventional mobile communications network institute.Such as, immense unbounded vast ocean, the desert be desolate and uninhabited, by earthquake or tsunami the Code in Hazardous Special Locations such as city and battlefield surroundings that damages.

Time synchronization technique is one of important base support technology of wireless network, be not only the necessary condition ensureing that radio sensing network engineering is normally run, and synchronization accuracy directly affects the performance of other middleware.In distributed wireless ad hoc network network system, due to dispersiveness physically, system cannot provide the unified time for separate module.And each module has the local clock of oneself, the local clock of each module is due to the difference of clock speed and running environment, even if all calibrate unification when initial, but after a period of time, the local clock of all modules still there will be clock skew.In order to allow these modules again calibrate the unified time, must time synchronized operation be carried out, reaching the time slot alignment of all nodes of whole network.

The time mutually synchronization technology adopted in current ad-hoc network system mainly adopts glowworm swarm algorithm.But, adopt the Time synchronization technique of glowworm swarm algorithm to have following shortcoming: in wireless network, independent pulse signal cannot be monitored to, and meanwhile, existing technology is difficult to signal is shrunk in time a unlimited short pulse; Signal is transmitted by random wireless channel, and when the distance between node is larger, propagation delay just can not be left in the basket, and transmitting terminal distributes signal, and node receives immediately and cannot realize; Receiving terminal, after receiving signal, needs the time to carry out parse operation, also can not complete corresponding operating instantaneously.Which limits the application of firefly Time synchronization algorithm in wireless self-networking.

Therefore, how to improve traditional glowworm swarm algorithm, overcome it to the very sensitive shortcoming of the factors such as coupled delay, network topology and propagation delay, well can be applicable to wireless self-networking, just become the key issue that the present invention will study.

Summary of the invention

The object of the embodiment of the present invention is to provide a kind of method for synchronizing time for wireless self-networking and device, stablizes synchronous object to realize each node in wireless self-networking.Concrete technical scheme is as follows:

First aspect, the invention provides a kind of method for synchronizing time for wireless self-networking, be applied to the first node in wireless self-networking, described method comprises:

Intercept in the period in the current sync cycle, monitor the first synchronizing signal whether received from other node, wherein, any node in described wireless self-networking each synchronizing cycle experience all successively wait for the period, to self with exterior node send synchronizing signal signal transmit time segments, do not react period and monitoring and process the synchronizing signal self sent with exterior node intercept the period, described first synchronizing signal sends for the signal transmit time segments in this other nodes synchronizing cycles in office;

If so, then adjust the current phase place of described first node according to described first synchronizing signal, if phase place reaches threshold value, phase place zero setting after adjustment, enter the wait period of next synchronizing cycle in advance, be ready for sending synchronizing signal;

Otherwise, control described phase linearity and increase, when described phase place rises to threshold value, enter the wait period of next synchronizing cycle.

Further, described method also comprises:

In the signal transmit time segments in current sync cycle, node beyond self sends the second synchronizing signal, to make intercepting node that the period receives described second synchronizing signal based on described second synchronizing signal adjustment phase place, and when phase place is adjusted to threshold value, enter the wait period of next synchronizing cycle.

Further, the described current phase place adjusting described first node according to described first synchronizing signal comprises:

Control phase continuous linear increases, and during this period, carries out decoding to described first synchronizing signal, determines the sending node of described first synchronizing signal according to the identify label of node each in described wireless self-networking;

Based on described sending node, in the delay compensation list of setting up in advance, inquire about the corresponding make-up time;

After postponing the described make-up time, calculate phase increment;

According to described phase increment, described phase place is adjusted.

Further, according to following formulae discovery phase increment:

$\begin{array}{ccc}\mathrm{\ω}+\mathrm{\Δ}\mathrm{\ω}=min(\mathrm{\α}\·\mathrm{\ω}+\mathrm{\β},1)& with& \left\{\begin{array}{c}\mathrm{\α}=\exp (b\·\mathrm{\ϵ})\\ \mathrm{\β}=\frac{\exp (b\·\mathrm{\ϵ})-1}{\exp \left(b\right)-1}\end{array}\right.\end{array}$

Wherein, described ω is phase value before the adjustment of described first node, and described Δ ω is described phase increment, and described b is the constant between 0-3, and described ε is the constant between 0-0.25.

Further, the described wait window duration T of arbitrary synchronizing cycle _waitmeet:

$T_{wait}=T-\left(T_{Tx}+T_{dec}+T_{pro}^{\max }\right);$

Describedly do not react window duration T _refrmeet:

$T_{refr}>2\·T_{pro}^{\max };$

Describedly intercept window duration T _rxmeet:

T _Tx+T _wait+T _refr+T _Rx＝2T

Wherein said T is the time synchronized cycle of described wireless self-networking, described T _txfor the described signal transmit time segments duration, described T _decfor the time that described first node carries out needed for decoding to described first synchronizing signal, described in for maximum communication distance in described wireless self-networking two nodes between propagation delay.

Further, described method also comprises:

By training sequence and the training sequence sending other nodes described in described first synchronization message of default described first node, calculate the propagation delay corresponding to described first synchronization message;

Based on calculated propagation delay, upgrade first node described in described delay compensation list to the make-up time sending other nodes described in described first synchronization message;

Wherein, upgrading the formula that the described make-up time utilizes is:

$T_{com}^{i,j}=\left\{\begin{array}{cc}{T}_{com}^{i,j}+{\mathrm{\&Delta;T}}_1& if\left(T_{com}^{i,j}+T_{pro}^{i,j}<T_{pro}^{\max }\right)\\ T_{com}^{i,j}& if\left(T_{com}^{i,j}+T_{pro}^{i,j}=T_{pro}^{\max }\right)\\ T_{com}^{i,j}-{\mathrm{\&Delta;T}}_2& if\left(T_{com}^{i,j}+T_{pro}^{i,j}>T_{pro}^{\max }\right)\end{array}\right.$

Wherein, described i is described first node, and described j is other nodes described sending described first synchronization message, described in for the propagation delay corresponding to described first synchronization message, described in for described first node is to the make-up time sending other nodes described in described first synchronization message, described Δ T ₁for increasing the adjustment step footpath during make-up time, described Δ T ₂for reducing the adjustment step footpath during make-up time, and Δ T ₁> Δ T ₂.

Further, described method also comprises:

When the phase place adjusted according to described first synchronizing signal does not reach threshold value, control phase continues linear growth, during this period, continues to perform the step monitoring the first synchronizing signal whether received from other node.

Second aspect, the invention provides a kind of time synchronism apparatus for wireless self-networking, be applied to the first node in wireless self-networking, described device comprises:

Monitor module, for intercepting in the period in the current sync cycle, monitor the first synchronizing signal whether received from other node, wherein, any node in described wireless self-networking each synchronizing cycle experience all successively wait for the period, to self with exterior node send synchronizing signal signal transmit time segments, do not react period and monitoring and process the synchronizing signal self sent with exterior node intercept the period, described first synchronizing signal sends for the signal transmit time segments in this other nodes synchronizing cycles in office;

Adjusting module, for in response to the first synchronizing signal received from other node, the current phase place of described first node is adjusted according to described first synchronizing signal, if phase place reaches threshold value after adjustment, phase place zero setting, enter the wait period of next synchronizing cycle in advance, be ready for sending synchronizing signal;

First control module, in response to the first synchronizing signal do not received from other node, controls described phase linearity and increases, and when described phase place rises to threshold value, enters the wait period of next synchronizing cycle.

Further, described adjusting module comprises:

Implementation sub-module, increases for control phase continuous linear, during this period, carries out decoding to described first synchronizing signal, determine the sending node of described first synchronizing signal according to the identify label of node each in described wireless self-networking;

Inquiry submodule, for based on described sending node, inquires about the corresponding make-up time in the delay compensation list of setting up in advance;

Calculating sub module, after postponing the described make-up time, calculates phase increment;

Adjustment submodule, for adjusting described phase place according to described phase increment.

Further, described device also comprises:

Second control module, during for not reaching threshold value when the phase place adjusted according to described first synchronizing signal, control phase continues linear growth, during this period, continues to perform the step monitoring the first synchronizing signal whether received from other node.

The method for synchronizing time for wireless self-networking that the embodiment of the present invention provides and device, the sensitive question that in conventional wireless network, Time synchronization algorithm changes time delay and network topology structure can be solved, break the restriction that synchronous convergence precision is limited to maximum transmitted time delay in network, break away from the dependence of conventional wireless network to outside time synchronizing signal, split-second precision mutually synchronization in the net realizing wireless self-networking, for the communication between nodes provides the foundation and technical support.Certainly, arbitrary product of the present invention is implemented or method must not necessarily need to reach above-described all advantages simultaneously.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 shows the exemplary process diagram of a kind of method for synchronizing time for wireless self-networking provided according to the embodiment of the present invention;

Fig. 2 shows each node periodic state distribution schematic diagram;

Fig. 3 shows node state change procedure schematic diagram;

Fig. 4 shows synchronous regime lower node state variation schematic diagram; And

Fig. 5 shows the functional module framework schematic diagram of a kind of time synchronism apparatus for wireless self-networking provided according to the embodiment of the present invention.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.

Please refer to Fig. 1, it illustrates the exemplary process diagram of a kind of method for synchronizing time for wireless self-networking that the embodiment of the present invention provides.The present embodiment first node be mainly applied in this way in wireless self-networking is that example illustrates, is understandable that, in wireless self-networking, any node all can perform method for synchronizing time given by the present embodiment as first node.

As shown in Figure 1, a kind of method for synchronizing time for wireless self-networking that the embodiment of the present invention provides, can comprise the steps:

Step 101, intercepts in the period in the current sync cycle, monitors the first synchronizing signal whether received from other node.

In order to realize time synchronized, the first node in wireless self-networking periodically carries out time synchronized with other nodes.Further, after entering a synchronizing cycle, first node can be intercepted in the period in the current sync cycle, monitors the first synchronizing signal whether received from other node, and performs different operations according to different snoop results.

It should be noted that, any node in wireless self-networking each synchronizing cycle all can experience successively wait for the period, to self with exterior node send synchronizing signal signal transmit time segments, do not react period and monitoring and process the synchronizing signal self sent with exterior node intercept the period.Specifically, a stable synchronous convergence state finally can be maintained in order to realize all nodes in network, the strategy that the present invention adopts can carry out a static compensation at transmitting terminal, also namely first each node can experience a wait period in each synchronizing cycle, within the wait period, the phase place of node does not change, remain 0, and the synchronizing signal do not received from other node, after experienced by the wait period, node just enters transmit time segments, starts to send synchronizing signal to other node.Further,

In the signal transmit time segments of synchronizing cycle, node can send the second synchronizing signal to other node beyond self, to make intercepting node that the period receives the second synchronizing signal based on the second synchronizing signal adjustment phase place, and when phase place is adjusted to threshold value, enter the wait period of next synchronizing cycle.

In order to solve in wireless self-networking, due to the propagation delay of can not ignore all may be there is between any two nodes and the avalanche effect caused, invention introduces and not react the period.Avalanche effect refers to: suppose that the propagation delay between node 1 and node 2 is T _pro, in 0 moment, node 1 triggers and have sent a synchronizing signal, at moment T _pro, this signal arrives node 2, and node 2 just in time reaches threshold value after producing SPA sudden phase anomalies, and trigger and send a synchronizing signal, this signal is at 2T _promoment is received by node 1, may cause its repeated trigger.And this repeated trigger is to the synchronous not effect of realization, on the contrary, whole network signal can be increased and transmit congested probability.

Therefore, after experience transmit time segments, node can enter and not react the period.Not reacting in the period, the phase function of node remains 0, even if the signal received from other node does not also change.After node sends signal, adding this state just can keeping system stability.Do not react window duration T _refrdemand fulfillment:

$T_{refr}>2\&CenterDot;T_{pro}^{\max }$

Wherein, represent the propagation delay of point-to-point maximum in network, also namely within the scope of efficient communication lie farthest away two nodes between propagation delay.According to the network size size of application, maximum propagation time delay can be determined by the maximum communication radius of nodes and then the minimum value of not reacting window duration can be determined.

After experience does not react the period, node enters intercepts the period.Intercepting in the period, node can monitor the first synchronizing signal whether received from other node.Above-mentioned first synchronizing signal can send for the signal transmit time segments in this other node synchronizing cycle in office.

Please refer to Fig. 2, it illustrates each node periodic state distribution schematic diagram.As shown in Figure 2, within the whole 2T cycle, each node all can experience wait period, signal transmit time segments, not react period and the period of intercepting.Wherein, do not react in the period at a node, time sequencing there occurs following event: its synchronizing signal sent is transferred to receiving node through wireless channel, T consuming time _pro; Receiving node completes the decoding to synchronizing signal, T consuming time _dec; Receiving node, after the transmission time of this synchronizing signal of dynamic compensation, completes the increasing amount adjustment of phase place, T consuming time _comp.Alternatively or additionally, within a synchronizing cycle, wait for window duration T _waitmeet:

$T_{wait}=T-\left(T_{Tx}+T_{dec}+T_{pro}^{\max }\right);$

Intercept window duration T _rxmeet:

T _Tx+T _wait+T _refr+T _Rx＝2T

Wherein T is the synchronizing cycle of wireless self-networking, can be arranged the size of T rational synchronizing cycle by the time relationship between day part.T _txfor the signal transmit time segments duration, by the size of synchronization signal data bag and the transmission rate of node, synchronizing signal transmitting time can be calculated, i.e. signal transmit time segments duration T _tx.

Node carries out the time T needed for decoding to the first synchronizing signal _deccan complete and draw the average time spent needed for synchronizing signal decoding by calculating each node.

Step 102, in response to the first synchronizing signal received from other node, according to the current phase place of the first synchronizing signal adjustment first node, if phase place reaches threshold value after adjustment, phase place zero setting, enters the wait period of next synchronizing cycle in advance, is ready for sending synchronizing signal.

In the present embodiment, when after the first synchronizing signal that first node receives from other node, can according to the current phase place of the first synchronizing signal adjustment first node, and, if phase place reaches threshold value after adjustment, then by phase place zero setting, and the wait period that first node enters next synchronizing cycle in advance can be controlled, be ready for sending synchronizing signal.

In an optional implementation of the present embodiment, the current phase place of first node can be adjusted according to the first synchronizing signal: first node controls its phase place continuous linear and increases according to following step, during this period, decoding is carried out to the first synchronizing signal, determines the sending node of the first synchronizing signal according to the identify label of node each in wireless self-networking; Based on sending node, in the delay compensation list of setting up in advance, inquire about the corresponding make-up time; After the delay compensation time, calculate phase increment; According to phase increment, phase place is adjusted.

After first node receives the first synchronizing signal from other node, first need to resolve the first synchronizing signal.First node, after completing the parsing to the first synchronizing signal, can't enter horizontal phasing control immediately, but needs to postpone a period of time, to solve the different problem of propagation delay between nodes.Particularly, each node is being established locally a delay compensation list, when wherein have recorded the synchronizing signal received from each neighbors, needs the corresponding time compensated.After every minor node receives synchronizing signal, first decoding is carried out to signal, judge that signal is from which neighbors, then finds the corresponding make-up time in table, after then postponing this time, increasing amount adjustment is carried out to phase place.

In order to solve the identification problem of signal source, when wireless self-networking builds, according to node number total in network, identify label sequence can be set.What dynamic compensation realized is, when not reaching maximum to each propagation delay, carry out adaptive compensation, to be absolutely necessary a step so judge that signal is originated.After receiving node receives the signal of band identify label, solve identification information, just can judge that signal is originated, then adaptive propagation delay to be compensated.

Complete after the decoding of the first synchronizing signal and dynamic compensation, first node can calculate corresponding phase increment.In the present embodiment, can according to following formulae discovery phase increment:

$\begin{array}{ccc}\mathrm{\&omega;}+\mathrm{\&Delta;}\mathrm{\&omega;}=min(\mathrm{\&alpha;}\&CenterDot;\mathrm{\&omega;}+\mathrm{\&beta;},1)& with& \left\{\begin{array}{c}\mathrm{\&alpha;}=\exp (b\&CenterDot;\mathrm{\&epsiv;})\\ \mathrm{\&beta;}=\frac{\exp (b\&CenterDot;\mathrm{\&epsiv;})-1}{\exp \left(b\right)-1}\end{array}\right.\end{array}$

Wherein, ω is phase value before the adjustment of first node, and Δ ω is phase increment, and b is the constant between 0-3, and ε is the constant between 0-0.25.B represents dissipation factor, and ε represents amplitude increment.These two parameters are used for adjusting interactional intensity between each node.In the listen period of first node, when receiving the synchronizing signal from other nodes, after being delayed the corresponding make-up time, according to current phase value, to oneself one, phase place increment Delta ω rapidly, oscillator is made to change original trigger instants and trigger in advance.Phase increment Δ ω depends on that first node receives the current phase place in neighbors synchronizing signal moment, and the time required for reaching synchronously and b ε are inversely proportional to.

Alternatively or additionally, first node has also needed the renewal of delay compensation list after completing delay compensation, phase place adjustment.First by the training sequence of the training sequence of default first node with other nodes of transmission the first synchronization message, the propagation delay corresponding to the first synchronization message can be calculated.Then based on calculated propagation delay, in the list of renewal delay compensation, first node is to the make-up time of other nodes of transmission first synchronization message.Wherein, upgrading the formula that utilizes of make-up time is:

$T_{com}^{i,j}=\left\{\begin{array}{cc}{T}_{com}^{i,j}+{\mathrm{\&Delta;T}}_1& if\left(T_{com}^{i,j}+T_{pro}^{i,j}<T_{pro}^{\max }\right)\\ T_{com}^{i,j}& if\left(T_{com}^{i,j}+T_{pro}^{i,j}=T_{pro}^{\max }\right)\\ T_{com}^{i,j}-{\mathrm{\&Delta;T}}_2& if\left(T_{com}^{i,j}+T_{pro}^{i,j}>T_{pro}^{\max }\right)\end{array}\right.$

Wherein, i is first node, and j is other nodes of transmission first synchronization message, for the propagation delay corresponding to the first synchronization message, for first node is to the make-up time of other nodes of transmission first synchronization message, Δ T ₁for increasing the adjustment step footpath during make-up time, Δ T ₂for reducing the adjustment step footpath during make-up time, and Δ T ₁> Δ T ₂.

Along with the change of network state, time delay estimated value is in the process of more and more convergence exact value, and offset also along with change, dynamically updates.Time initial, the value compensating list is all 0, each Received signal strength, while adjustment phase place, is also upgrading list.Δ T ₁with Δ T ₂for the minimum time fragment that maximum propagation time delay is divided into, this value choose the speed and precision that can affect convergence.As can be seen from above-mentioned formula, Δ T is less, and final the obtained make-up time is more accurate, and the compensation precision reached is also higher.Δ T is larger, does not need iteration many times to upgrade, and the make-up time just very close to theoretical value, can regulate the speed obviously faster.In reality, if require very high for synchronization accuracy, and be not strict with for the time reaching convergence, then we can carry out less segmentation to maximum propagation time delay, and namely Δ T setting is less.If need to reach synchronous regime fast, and more relatively low to the requirement of precision, then can compensation step footpath be arranged a little greatly a bit.

In the present embodiment, the introducing of training sequence is the propagation delay in order to calculate between two nodes.When wireless self-networking builds, can arrange oneself independently training sequence for each node in network, it changes in time.In network, each node can at oneself local training sequence maintaining all nodes, when receiving the synchronizing signal from neighbors, can determine signal is from which node according to identify label signal, the synchronizing sequence extracted in the training sequence of local this node maintained and Received signal strength is found to carry out associative operation, if time delay is 0, now two sequences should be the same, after relevant, its frequency domain peak value can in the position of 0, but because time delay, they are different, now peak value can depart from 0 position, and namely bias can be converted into time delay.Therefore, when first node receives the synchronizing signal of other node, can be carried out related calculation by the training sequence extracted in the local training sequence maintained and the signal received, according to the peakdeviation amount occurred after related operation, the propagation time T that signal experiences can be estimated aloft _pro.In receiving terminal synchronizing process, because network is in asynchronous regime, i.e. the time slot of all nodes not yet complete matching, the propagation delay calculated by training sequence may be a general estimated value.Along with the continuation of synchronizing process, more and more close to Complete Synchronization between node, this value also more and more will level off to actual exact value.

Be appreciated that when first node does not reach threshold value according to the phase place that the first synchronizing signal adjusts, it control phase can continue linear growth.And during this period, can continue to perform the step monitoring the first synchronizing signal whether received from other node.

Step 103, control phase linear growth, when phase place rises to threshold value, enters the wait period of next synchronizing cycle.

In the present embodiment, if first node does not receive the first synchronizing signal from other node, then intercepting in the period, controlling its phase linearity and increasing, when phase place rises to threshold value, enter the wait period of next synchronizing cycle.

Particularly, according to intercepting window duration T _listen, setup times phase function ω (t), meets:

$\frac{d\mathrm{\&omega;}\left(t\right)}{dt}=T_{listen}$

Namely ω (t) is the linear function about the time.Along with time t by 0 to T _listen, the phase place of node by 0 linear growth to maximum ω _th.When after arrival threshold value, node will enter the wait period of next synchronizing cycle, and meanwhile, the phase function of node remains 0.

As mentioned above, in the present embodiment, the initial condition of each node is randomly dispersed between 0-2T, is namely waiting for period, signal transmit time segments, is not reacting random distribution between period and the period of intercepting four kinds of states, and be in the random site of often kind of state.

Please refer to Fig. 3, it illustrates node state change procedure schematic diagram.Be described with first node, as shown in Figure 3, through after a period of time, arbitrarily intercepting a segment length is the time of 4T, and first node waits for period, transmit time segments and after not reacting the period, at τ+t experienced by ₁moment enters intercepts the period, and at this moment in section, first node does not receive the synchronizing signal from neighbors, and phase place rises to threshold value along with linearly, and in τ+2T time trigger, node enters the wait period of next synchronizing cycle, completes the adjustment in epicycle cycle.

As shown in Figure 3, be described with first node, first node, in the τ+2T moment, triggers and enters wait period of next cycle, at the T that waits for a period of time _waitafter, at τ+t ₂moment starts to send synchronizing signal, contains identify label and training sequence.Then through not reacting the period, first node again enters and intercepts the period.At this moment in section, have received the synchronizing signal from neighbors.This signal from being sent out node sends, T when have passed through transmission _tx, propagation time T _pro, at τ+t ₃in the moment, received by first node.Following first node starts to carry out decoding to synchronizing signal, elapsed time T _dec, decode procedure completes.Now, node can't enter horizontal phasing control immediately, but is first determined the signal source of this signal by identify label signal, and following first node starts to search local delay compensation list, have found the make-up time T to sending node in lists _comp, continue to wait for T _comptime span.During this period, the phase place of first node still along with the time is at linear growth, when reaching the τ+t in Fig. 3 ₄in the moment, node is according to current phase place ω (τ+t ₄), by formula

$\begin{array}{ccc}\mathrm{\&omega;}\left(\mathrm{\&tau;}+t_4^{+}\right)=\mathrm{\&omega;}(\mathrm{\&tau;}+t_4)+\mathrm{\&Delta;}\mathrm{\&omega;}=min(\mathrm{\&alpha;}\&CenterDot;\mathrm{\&omega;}\left(t_4\right)+\mathrm{\&beta;},1)& with& \left\{\begin{array}{c}\mathrm{\&alpha;}=\exp \left(b\&CenterDot;\mathrm{\&epsiv;}\right)\\ \mathrm{\&beta;}=\frac{\exp \left(b\&CenterDot;\mathrm{\&epsiv;}\right)-1}{\exp \left(b\right)-1}\end{array}\right.\end{array}$

Calculate the phase place after adjustment now phase place does not still reach threshold value ω _th, first node will continue the linear in increasing of phase place.Intercept the period be left in the time at this, first node does not receive the synchronizing signal of other neighbors again, at τ+t ₅in the moment, the phase place of first node reaches threshold value ω _th, trigger and enter wait period of next synchronizing cycle in advance.

As seen from Figure 3, if in this synchronizing cycle there there is no and other node interactive information first node, phase linearity rises to triggering and then occurs in the τ+4T moment, in view of this synchronizing signal of another node allows the triggering of first node be advanced by, and then makes the initial time of next synchronizing cycle be advanced by (4T-t ₃) time.By this adjustment, change the time slot aligned condition between all nodes.In MANET, all nodes continuous iteration is in this way mutual, and be finally divided into two groups, triggering intervals is just one-period T.

Please refer to Fig. 4, it illustrates synchronous regime lower node state variation schematic diagram.As shown in Figure 4, in the τ moment, first node triggers, and experienced by after waiting for the period, at τ+t ₁in the moment, start to send synchronizing signal.This signal is through T _propropagation delay, at τ+t ₂moment arrives Section Point.Section Point 2 is through T _decthe decoding of time complete pair signals, then according to the time delay T found from delay compensation list _comp, after postponing this time, just in the phase place of τ+T moment knot modification.And now node 2 is by natural linear growth, phase place also just in time arrives threshold value, according to formula

$\begin{array}{ccc}\mathrm{\&omega;}(\mathrm{\&tau;}+T^{+})=\mathrm{\&omega;}(\mathrm{\&tau;}+T)+\mathrm{\&Delta;}\mathrm{\&omega;}=min(\mathrm{\&alpha;}\&CenterDot;\mathrm{\&omega;}(\mathrm{\&tau;}+T)+\mathrm{\&beta;},1)& with& \left\{\begin{array}{c}\mathrm{\&alpha;}=\exp (b\&CenterDot;\mathrm{\&epsiv;})\\ \mathrm{\&beta;}=\frac{\exp (b\&CenterDot;\mathrm{\&epsiv;})-1}{\exp \left(b\right)-1}\end{array}\right.\end{array}$

Find that the phase place of this synchronizing signal to Section Point does not just have an impact, i.e. the synchronizing signal impact produced and the effect Complete Synchronization linearly certainly increased.Conversely, when Section Point sends synchronizing information, just impact is not produced to first node yet.Along with iteration constantly continues, between all nodes, all reach this synchronous regime, then whole network just reaches the stable state of Complete Synchronization.

The method for synchronizing time for wireless self-networking that the present embodiment provides, the sensitive question that in conventional wireless network, Time synchronization algorithm changes time delay and network topology structure can be solved, break the restriction that synchronous convergence precision is limited to maximum transmitted time delay in network, break away from the dependence of conventional wireless network to outside time synchronizing signal, split-second precision mutually synchronization in the net realizing wireless self-networking, for the communication between nodes provides the foundation and technical support.

Please refer to Fig. 5, the functional module framework schematic diagram of a kind of time synchronism apparatus 500 for wireless self-networking provided according to the embodiment of the present invention is provided.

As shown in Figure 5, the time synchronism apparatus 500 for wireless self-networking that the present embodiment provides comprises: monitor module 510, adjusting module 520 and the first control module 530.

Monitor module 510 for intercepting in the period in the current sync cycle, monitor the first synchronizing signal whether received from other node, wherein, any node in wireless self-networking each synchronizing cycle experience all successively wait for the period, to self with exterior node send synchronizing signal signal transmit time segments, do not react period and monitoring and process the synchronizing signal self sent with exterior node intercept the period, the first synchronizing signal sends for the signal transmit time segments in this other nodes synchronizing cycles in office.

Adjusting module 520 is in response to the first synchronizing signal received from other node, according to the current phase place of the first synchronizing signal adjustment first node, if phase place reaches threshold value, phase place zero setting after adjustment, enter the wait period of next synchronizing cycle in advance, be ready for sending synchronizing signal.

First control module 530 is in response to the first synchronizing signal do not received from other node, and control phase linear growth, when phase place rises to threshold value, enters the wait period of next synchronizing cycle.

In an optional implementation of the present embodiment, adjusting module 520 comprises:

Implementation sub-module, increases for control phase continuous linear, during this period, carries out decoding to the first synchronizing signal, determine the sending node of the first synchronizing signal according to the identify label of node each in wireless self-networking;

Inquiry submodule, for based on sending node, inquires about the corresponding make-up time in the delay compensation list of setting up in advance;

Calculating sub module, after the delay compensation time, calculates phase increment;

Adjustment submodule, for adjusting phase place according to phase increment.

In an optional implementation of the present embodiment, the time synchronism apparatus 500 for wireless self-networking also comprises:

Computing module, for training sequence and the training sequence sending other nodes described in described first synchronization message of the described first node by presetting, calculates the propagation delay corresponding to described first synchronization message;

Update module, for based on calculated propagation delay, upgrades first node described in described delay compensation list to the make-up time sending other nodes described in described first synchronization message;

Wherein, upgrading the formula that the described make-up time utilizes is:

$T_{com}^{i,j}=\left\{\begin{array}{cc}{T}_{com}^{i,j}+{\mathrm{\&Delta;T}}_1& if\left(T_{com}^{i,j}+T_{pro}^{i,j}<T_{pro}^{\max }\right)\\ T_{com}^{i,j}& if\left(T_{com}^{i,j}+T_{pro}^{i,j}=T_{pro}^{\max }\right)\\ T_{com}^{i,j}-{\mathrm{\&Delta;T}}_2& if\left(T_{com}^{i,j}+T_{pro}^{i,j}>T_{pro}^{\max }\right)\end{array}\right.$

Wherein, described i is described first node, and described j is other nodes described sending described first synchronization message, described in for the propagation delay corresponding to described first synchronization message, described in for described first node is to the make-up time sending other nodes described in described first synchronization message, described Δ T ₁for increasing the adjustment step footpath during make-up time, described Δ T ₂for reducing the adjustment step footpath during make-up time, and Δ T ₁> Δ T ₂.

In an optional implementation of the present embodiment, the time synchronism apparatus 500 for wireless self-networking also comprises:

Second control module, for when the phase place adjusted according to the first synchronizing signal does not reach threshold value, control phase continues linear growth, during this period, continues to perform the step monitoring the first synchronizing signal whether received from other node.

The time synchronism apparatus for wireless self-networking that the present embodiment provides, the sensitive question that in conventional wireless network, Time synchronization algorithm changes time delay and network topology structure can be solved, break the restriction that synchronous convergence precision is limited to maximum transmitted time delay in network, break away from the dependence of conventional wireless network to outside time synchronizing signal, split-second precision mutually synchronization in the net realizing wireless self-networking, for the communication between nodes provides the foundation and technical support.

It should be noted that, in this article, the such as relational terms of first and second grades and so on is only used for an entity or operation to separate with another entity or operating space, and not necessarily requires or imply the relation that there is any this reality between these entities or operation or sequentially.And, term " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thus make to comprise the process of a series of key element, method, article or equipment and not only comprise those key elements, but also comprise other key elements clearly do not listed, or also comprise by the intrinsic key element of this process, method, article or equipment.When not more restrictions, the key element limited by statement " comprising ... ", and be not precluded within process, method, article or the equipment comprising described key element and also there is other identical element.

Each embodiment in this specification all adopts relevant mode to describe, between each embodiment identical similar part mutually see, what each embodiment stressed is the difference with other embodiments.Especially, for system embodiment, because it is substantially similar to embodiment of the method, so description is fairly simple, relevant part illustrates see the part of embodiment of the method.

The foregoing is only preferred embodiment of the present invention, be not intended to limit protection scope of the present invention.All any amendments done within the spirit and principles in the present invention, equivalent replacement, improvement etc., be all included in protection scope of the present invention.

Claims (10)

1. for a method for synchronizing time for wireless self-networking, it is characterized in that, be applied to the first node in wireless self-networking, described method comprises:

Intercept in the period in the current sync cycle, monitor the first synchronizing signal whether received from other node, wherein, any node in described wireless self-networking each synchronizing cycle experience all successively wait for the period, to self with exterior node send synchronizing signal signal transmit time segments, do not react period and monitoring and process the synchronizing signal self sent with exterior node intercept the period, described first synchronizing signal sends for the signal transmit time segments in this other nodes synchronizing cycles in office;

If so, then adjust the current phase place of described first node according to described first synchronizing signal, if phase place reaches threshold value, phase place zero setting after adjustment, enter the wait period of next synchronizing cycle in advance, be ready for sending synchronizing signal;

Otherwise, control described phase linearity and increase, when described phase place rises to threshold value, enter the wait period of next synchronizing cycle.

2. method according to claim 1, is characterized in that, also comprises:

In the signal transmit time segments in current sync cycle, node beyond self sends the second synchronizing signal, to make intercepting node that the period receives described second synchronizing signal based on described second synchronizing signal adjustment phase place, and when phase place is adjusted to threshold value, enter the wait period of next synchronizing cycle.

3. method according to claim 1 and 2, is characterized in that, the described current phase place adjusting described first node according to described first synchronizing signal comprises:

Control phase continuous linear increases, and during this period, carries out decoding to described first synchronizing signal, determines the sending node of described first synchronizing signal according to the identify label of node each in described wireless self-networking;

Based on described sending node, in the delay compensation list of setting up in advance, inquire about the corresponding make-up time;

After postponing the described make-up time, calculate phase increment;

According to described phase increment, described phase place is adjusted.

4. method according to claim 3, is characterized in that, according to following formulae discovery phase increment:

$\begin{array}{ccc}\mathrm{\&omega;}+\mathrm{\&Delta;}\mathrm{\&omega;}=min(\mathrm{\&alpha;}\&CenterDot;\mathrm{\&omega;}+\mathrm{\&beta;},1)& with& \left\{\begin{array}{c}\mathrm{\&alpha;}=\exp (b\&CenterDot;\mathrm{\&epsiv;})\\ \mathrm{\&beta;}=\frac{\exp (b\&CenterDot;\mathrm{\&epsiv;})-1}{\exp \left(b\right)-1}\end{array}\right.\end{array}$

Wherein, described ω is phase value before the adjustment of described first node, and described Δ ω is described phase increment, and described b is the constant between 0-3, and described ε is the constant between 0-0.25.

5. method according to claim 3, is characterized in that, the described wait window duration T of arbitrary synchronizing cycle _waitmeet:

$T_{wait}=T-(T_{Tx}+T_{dec}+T_{pro}^{\max });$

Describedly do not react window duration T _refrmeet:

$T_{refr}>2\&CenterDot;T_{pro}^{\max };$

Describedly intercept window duration T _rxmeet:

T _Tx+T _wait+T _refr+T _Rx＝2T

Wherein, described T is the synchronizing cycle of described wireless self-networking, described T _txfor the described signal transmit time segments duration, described T _decfor the time that described first node carries out needed for decoding to described first synchronizing signal, described in for maximum communication distance in described wireless self-networking two nodes between propagation delay.

6. method according to claim 5, is characterized in that, described based on described sending node, and inquire about the corresponding make-up time in the delay compensation list of setting up in advance after, described method also comprises:

By training sequence and the training sequence sending other nodes described in described first synchronization message of default described first node, calculate the propagation delay corresponding to described first synchronization message;

Based on calculated propagation delay, upgrade first node described in described delay compensation list to the make-up time sending other nodes described in described first synchronization message;

Wherein, upgrading the formula that the described make-up time utilizes is:

$T_{com}^{i,j}=\left\{\begin{array}{cc}{T}_{com}^{i,j}+{\mathrm{\&Delta;T}}_1& if\left(T_{com}^{i,j}+T_{pro}^{i,j}<T_{pro}^{\max }\right)\\ T_{com}^{i,j}& if\left(T_{com}^{i,j}+T_{pro}^{i,j}=T_{pro}^{\max }\right)\\ T_{com}^{i,j}-{\mathrm{\&Delta;T}}_2& if\left(T_{com}^{i,j}+T_{pro}^{i,j}>T_{pro}^{\max }\right)\end{array}\right.$

Wherein, described i is described first node, and described j is other nodes described sending described first synchronization message, described in for the propagation delay corresponding to described first synchronization message, described in for described first node is to the make-up time sending other nodes described in described first synchronization message, described Δ T ₁for increasing the adjustment step footpath during make-up time, described Δ T ₂for reducing the adjustment step footpath during make-up time, and Δ T ₁> Δ T ₂.

7. method according to claim 1, is characterized in that, described method also comprises:

When the phase place adjusted according to described first synchronizing signal does not reach threshold value, control phase continues linear growth, during this period, continues to perform the step monitoring the first synchronizing signal whether received from other node.

8. for a time synchronism apparatus for wireless self-networking, it is characterized in that, be applied to the first node in wireless self-networking, described device comprises:

Monitor module, for intercepting in the period in the current sync cycle, monitor the first synchronizing signal whether received from other node, wherein, any node in described wireless self-networking each synchronizing cycle experience all successively wait for the period, to self with exterior node send synchronizing signal signal transmit time segments, do not react period and monitoring and process the synchronizing signal self sent with exterior node intercept the period, described first synchronizing signal sends for the signal transmit time segments in this other nodes synchronizing cycles in office;

Adjusting module, for in response to the first synchronizing signal received from other node, the current phase place of described first node is adjusted according to described first synchronizing signal, if phase place reaches threshold value after adjustment, phase place zero setting, enter the wait period of next synchronizing cycle in advance, be ready for sending synchronizing signal;

First control module, in response to the first synchronizing signal do not received from other node, controls described phase linearity and increases, and when described phase place rises to threshold value, enters the wait period of next synchronizing cycle.

9. device according to claim 8, is characterized in that, described adjusting module comprises:

Implementation sub-module, increases for control phase continuous linear, during this period, carries out decoding to described first synchronizing signal, determine the sending node of described first synchronizing signal according to the identify label of node each in described wireless self-networking;

Inquiry submodule, for based on described sending node, inquires about the corresponding make-up time in the delay compensation list of setting up in advance;

Calculating sub module, after postponing the described make-up time, calculates phase increment;

Adjustment submodule, for adjusting described phase place according to described phase increment.

10. device according to claim 8, is characterized in that, described device also comprises:

Second control module, during for not reaching threshold value when the phase place adjusted according to described first synchronizing signal, control phase continues linear growth, during this period, continues to perform the step monitoring the first synchronizing signal whether received from other node.